Biological vectors have proven to be useful in many applications. Among these applications are whole genome screening, gene function studies, and gene therapy. When using these vectors, one preferably tries to transfer genes efficiently to the desired target cells. In order to increase efficiency, researchers have explored ways to use both viral and non-viral vectors.
One of the areas that researchers have explored with great interest is the use of lentiviral vectors. Lentiviral vectors make use of lentiviral sequences and are a subclass of retroviral vectors. However, unlike other retroviruses, lentiviruses are able to integrate into the genome of both dividing and non-dividing cells. After entry into a cell, the viral genome, which is in the form of RNA, is reverse transcribed to generate DNA, which is then inserted into the host genome. Because lentiviral vectors can cause their sequences to be integrated into non-dividing cells, they are particularly promising for many applications.
With the basic means for working with lentiviruses now well-known to persons of ordinary skill in the art, researchers have created whole genome expression libraries that contain small pieces of the genome in large numbers of vectors such as lentiviruses. These whole genome expression libraries are well-known as useful research tools and are becoming increasingly popular for high content screening, as well as for more focused investigations of gene function.
Currently, whole genome libraries are limited to a static choice of all functional components linked to the genetic content including promoter, reporter, selection marker and more during the production of the library. Unfortunately, under currently known techniques it is both logistically and financially impractical to create whole genome content libraries containing a variety of promoters, reporters and drug selection markers. This is a significant limitation because these components can greatly impact the performance and usefulness of the vectors in any given experimental setup. Thus, there is a need for new ways by which to create lentiviral vectors and libraries that have sufficient levels of variability.